Biosensors are devices for sensing and detecting biomolecules and operate on the basis of electronic, electrochemical, optical and mechanical detection principles. Biosensors that include transistors are sensors that electrically sense charges, photons, and mechanical properties of bio-entities or biomolecules. The sensor detects the concentration of bio-entities or biomolecules, or through interaction and reaction between specified reactants and bio-entities/biomolecules. Such biosensors are fast in signal conversion and can be manufactured using semiconductor processes and easily applied to integrated circuits and MEMS.
A field effect transistor (FET) includes a source, a drain and a gate and may be used as a sensor for various types of targets. A biologically sensitive field effect transistor, or bio-organic field effect transistor, (Bio-FET) is created to detect biomolecules, including, for example, H+, Ca2+, DNA, proteins and glucose. An electrolyte containing the molecule of interest is used as the Bio-FET gate.